Improved performance of AlGaN/GaN HEMT based H+ sensors by surface hydroxylation treatment

Abstract

The surface hydroxylation treatment effects on GaN and the AlGaN/GaN HEMT based H+ sensor was studied by water contact angle measurement, Atomic Force Microscope (AFM), X-ray photoelectron spectroscopy (XPS) and semiconductor characterization system (SCS). The water contact angle on GaN decreased from 41° to 9°, the rms roughness of GaN surface decreased from 0.75 nm to 0.70 nm, and the density of hydroxyl groups on the surface approached 5 times the original after the treatment of Sulfuric/Peroxide Mix (SPM) at 80 °C for 20 min due to the semi-quantitative analysis of XPS. The results of repeated measurements by SCS indicated that the repeatability of the AlGaN/GaN HEMT based H+ sensor could be improved by the SPM treatment. The current signal sensitivity rising from 46.7 μA/pH to 113.3 μA/pH shown that the sensitivity of the device was improved by the SPM treatment due to an increasing number of hydroxyl groups per unit area.